Cured emulsion copolymers having a plurality of activatable functional ester groups

ABSTRACT

An aqueous latex contains a functionalized copolymer prepared by emulsion polymerization. The copolymer can be applied to textile nonwoven materials and to various cellulosic substrates, and when utilized as a binder imparts enhanced properties thereto such as wet tensile strength, low temperature cure rates, and the like. The monomers generally forming the copolymer include at least two functional type monomers, one of which contains an activatable ester group, and at least one latex forming monomer.

CROSS REFERENCE

This application is a continuation of application Ser. No. 07/203,175filed May 20, 1988, now abandoned, which is a division of applicationSer. No. 07/025,249 filed Mar. 12, 1987, now U.S. Pat. No. 4,808,660,which is a continuation in part of U.S. Pat. No. 06/848,018 filed Apr.3, 1986, now abandoned.

FIELD OF THE INVENTION

The present invention relates to copolymers made from latex typemonomers and effective amounts of functional type monomers including amonomer containing an activatable ester group. The present inventionfurther relates to cured latexes thereof.

PRIOR ART

A series of articles, namely, Polymer Journal Volume 5, pages 186-194(1973); Volume 6, pages 412-418 (1974); Volume 7, pages 72-78 (1975) andVolume 10, pages 499-504 (1978), by Ogata, et al, generally relate tobeta-hetero atom containing diesters or dibasic acids which react undermild conditions with amines to form polyamides.

U.S. Pat. No. 3,422,139 to Talet, et al, relates toacrylamido-N-glycolic acids as well as N-methylol-acrylamido-N-glycolicacids and their use in treatment of paper.

European Patent Application No. 20,000 relates to ethylenicallyunsaturated monomers containing activated ester groups which are used tomake polymers and copolymers useful in coatings, adhesives, and thelike.

U.S. Pat. No. 4,254,003 to Fox relates to an aqueous dispersion ofpolymer particles wherein the polymer comprises both a) polar groupssuch as amine and ureido groups and b) poly(alkylene oxide) chainscovalently bonded to the polymer. Such dispersed polymers are useful inlatex paint compositions.

U.S. Pat. No. 4,443,623 to Photis relates to the preparation of methylacrylamidoglycolate methyl ether and a normally liquid product.

U.S. Pat. No. 4,522,973 to Ley relates to a low temperaturecrosslinkable emulsion containing a crosslinkage polymer derived from anactivated ester-containing vinyl monomer and including a crosslinkingagent having a plurality of groups therein each capable of lowtemperature reaction with the activated ester group.

The above documents do not disclose the polymerization of the variouscomonomers in an aqueous latex or the various unexpected physicalproperties obtained when a plurality of functional type monomers havingat least one monomer containing an activatable ester group therein isutilized at the levels employed in the present invention.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to provide a latextype copolymer prepared by emulsion polymerization containing anactivatable ester group.

It is another aspect of the present invention to provide a latex typecopolymer, as above, made from monomers forming a latex emulsion as wellas from a plurality of functional monomers, one of which has apolymerizable vinyl group and an activatable crosslinking ester group.

It is yet a further aspect of the present invention to provide a latextype copolymer, as above, which when applied to nonwoven textile andcellulosic substrates generally yields improved end use properties andcure rates.

It is still another aspect of the present invention to provide a latextype copolymer, as above, which has improved wet strength upon cure.

These and other aspects of the present invention will become apparentfrom the following detailed specification.

In general, a cured emulsion copolymer, comprises the cured emulsioncopolymer, said copolymer made from an effective amount of at least onelatex forming monomer and two or more functional type monomers, whereinat least one of said functional type monomers has a vinyl group thereinas well as an activatable ester group, and wherein at least one of saidfunctional type monomers are the various acrylamides, the variousmethacrylamides, the various vinyl ethers, the various non-saturatedmono or dicarboxylic acid, or combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart of the wet tensile strength utilizing MAGME andacrylic acid as set forth in Example 1.

FIG. 2 is a chart of the wet tensile strength utilizing MAGME andacrylamide as set forth in Example 2.

DISCUSSION OF DETAILS AND PREFERRED EMBODIMENTS

The copolymers of the present invention are suitable for use as aqueousdispersions or as latexes, as well as for various applications thereof.The functionalized copolymer of the present invention, that is, theemulsion copolymer is made from one or more latex forming monomers andtwo or more functional type monomers wherein at least one of saidfunctional type monomers has an activatable ester group. Accordingly,the amount of the different types of monomers utilized, for example thelatex forming monomers will be based upon 100 parts by weight of thetotal monomers (PHM) utilized in forming the functionalized copolymer ofthe present invention. It is thus to be understood that hereinafter"total monomer" refers to all of the monomers, that is the latex formingmonomers and the two or more functional type monomers utilized informing the functionalized copolymer of the present invention.

The latex forming monomers are known to the art and to the literature.One suitable class of latex forming monomers are the various conjugateddienes. A suitable latex forming copolymer thereof is made with eitheranother conjugated diene monomer or preferably a vinyl substitutedaromatic monomer. When a conjugated diene comonomer is utilized, theamount thereof is from about 1% to about 99% by weight based upon thetotal monomers utilized in forming the functionalized copolymer of thepresent invention. Generally, the percentage description will beutilized hereinafter. When a vinyl substituted aromatic comonomer isutilized, the amount thereof is from about 0% or 1% to about 70% andpreferably from about 40% to about 65% by weight based upon the weightof the total monomers.

Considering the conjugated diene monomers, they generally have fromabout 4 to 8 carbon atoms and desirably from 4 to 6 carbon atoms.Examples of specific diene monomers include piperylene, isoprene,2,3-dimethyl-1,3-butadiene, and preferably 1,3-butadiene. Mixtures ofthese various conjugated dienes can also be utilized. Considering thevinyl substituted aromatic monomers which can be utilized in associationwith the conjugated dienes to form copolymers, generally they have from8 to about 12 total carbon atoms. Specific examples of such monomersinclude alpha methyl styrene, p-tertiary butyl styrene, methyl vinyltoluene, p-vinyl toluene, 3-ethyl styrene, and the like with styrenebeing preferred. Mixtures of such vinyl substituted aromatic monomerscan also be utilized. Considering the acrylonitrile monomers, variousderivatives thereof can be utilized such as methacrylonitrile,fumaronitrile, and the like.

Yet another suitable class of latex forming monomers are the variousvinyl esters. Inasmuch as the vinyl esters usually yield very high glasstransition temperature polymers, conventional amounts of plasticizersare generally utilized therewith such as dioctyl phthalate, or they arecopolymerized with various comonomers. Suitable vinyl esters includemonomers wherein the ester portion of the vinyl esters is desirably analkyl having from 1 to 8 carbon atoms. A preferred vinyl ester is vinylacetate. Examples of suitable comonomers include ethylene, and esters ofvarious mono or dicarboxylic acids. When a latex forming copolymer ismade from monomers of vinyl esters and ethylene, the amount of ethyleneis from about 10% to about 95% by weight based upon the weight of thetotal monomers. When latex forming copolymers are made from vinyl estermonomers and the esters of mono or dicarboxylic acid, the amount of themono or dicarboxylic acid esters is also from about 5% to about 50% byweight and desirably from about 15% to about 25% by weight based uponthe weight of the total monomers. Considering the various types ofesters of dicarboxylic acids which can be utilized as comonomers withthe vinyl esters, they are generally esters of dicarboxylic acids havingfrom 2 to 12 carbon atoms and desirably from 4 to 8 carbon atoms.Examples of such specific esters include diethyl fumarate, dibutylfumarate, and diethyl maleate, and dibutyl maleate.

Yet another class of suitable latex forming monomers are the ethylenemonomers. The ethylenes are generally always utilized in the form of acopolymer. Suitable latex forming copolymers are thus made utilizingethylene and vinyl chloride or various vinyl ester monomers. The amountof vinyl chloride monomers utilized with ethylene is from about 5% toabout 40% by weight based upon the weight of the total monomers. Theamount of the vinyl esters utilized with the ethylene is from about 5 toabout 90% by weight. The various types of vinyl ester monomers which canbe utilized to form copolymers with the ethylene monomers are as setforth hereinabove.

Although the various latex forming monomers generally form the bulk ofthe emulsion copolymer, that is from about 85% to about 99.5%, desirablyfrom about 90% to about 99%, and preferably from about 94% to about 97%by weight based upon the weight of the total monomers, it is anessential aspect of the present invention to utilize two or moredifferent types of functional monomers. A type of functional monomerwhich is always utilized in the present invention is characterized byhaving at least one vinyl group therein which is polymerizable and atleast one activatable ester group which enables the copolymer to becured or crosslinked; hereinafter referred to as an activatable estermonomer. The various activatable ester monomers include:

methyl acrylamidoglycolate (MAG)

ethyl acrylamidoclycolate (EAG)

butyl acrylamidoglycolate (BAG)

methyl acrylamidoglycolate methyl ether (MAGME)

butyl acrylamidoglycolate butyl ether (BAGBE)

methyl methacryloxyacetate

ethyl acrylamido-N-oxalate (N-ethyloxalyl acrylamide)

N,N'-Bis(ethyloxalyl)acrylamide

N-isopropyl, N-ethyloxalyl-3-propylamino methacrylamide

N-ethyloxalyl-N'-methyleneaminoacrylamide

ethyl N-2-ethyloxamatoacrylate

ethyl 3-pyruvylacrylate

ethyl methylenepyruvate

methyl acrylthiocarbonyloxyacetate (Methyl thiacryloxyacetate)

methyl thiacrylthioglycolate

methyl acryl-2-thioglycolate

methyl thiacrylamidoacetate

methyl acrylamidoglycolate thioether

methyl acrylamido-N-methylenethioglycolate

p-ethyl oxalyl styrene,

and the like. Additional examples include the above compounds wherein analkyl group having from 2 or 3 or 6 carbon atoms can be substituted forthe various "methyl", or "ethyl", groups.

When the functional containing monomer contains an activatable acidgroup thereon, specific examples of such compounds are acid derivativesof the above compounds, for example acrylamidoglycolic acid, and thelike.

The second or additional type of other functional monomers which areoptionally utilized include anionic monomers such as, the variousacrylamides, the various methacrylamides, the various vinyl ethers, andthe various non-saturated mono-or dicarboxylic acids. In lieu of theseanionic functional monomers, cationic monomers can be utilized as setforth hereinbelow. The total amount of such monomers including theactivatable ester functional monomers is generally small as from about0.5% to about 15% by weight. desirably from about 1 to about 10% byweight and preferably from about 3% to about 6% by weight based upon theweight of the total monomers.

The acrylamides and the methacrylamides include various alkylderivatives thereof having from 1 to 2 carbon atoms attached to eitherthe nitrogen atom and/or the vinyl group with specific examplesincluding dimethylacrylamide, methylene bisacrylamide, and the like.

The vinyl ethers are another class of vinyl type monomers which can beutilizsed in the present invention. They are generally represented bythe formula ##STR1## wherein;

R' is an alkyl group having from 1 to 6 carbon atoms, or a substitutedchloroalkyl group having a total of from 1 to 6 carbon atoms. Examplesof such specific vinyl ethers include n-butyl vinyl ether, vinylchloroethyl ethyl, and the like.

The acids which are utilized are an unsaturated monocarboxylic or adicarboxylic acid monomer containing a total of from 3 to about 6 carbonatoms and preferably from 3 to about 5 carbon atoms. Examples ofmonocarboxylic acids include acrylic acid and methacrylic acid. Examplesof dicarboxylic acids include fumaric acid, maleic acid, itaconic acid,and the like. Itaconic acid is preferred.

The amount of the acrylamides, the methacrylamides, the vinyl ethers, orthe mono or dicarboxylic acid monomers, or combinations thereofgenerally range from about 0.5% to about 5% by weight and preferablyfrom about 1% to about 3% by weight based upon the weight of the totalmonomer. Hence, the amount of activatable ester can be from about 1 toabout 10% with the amount of the second functional monomer being fromabout 0.5 to about 5% thereby achieving the overall range of from about0.5% to about 1.5% by weight of functional monomers.

The copolymer forming monomers of the present invention, that is theprimary and the optional secondary latex forming monomers, and the twoor more functional type monomers are reacted according to anyconventional free radical aqueous emulsion polymerization method knownto the art as well as to the literature to form the emulsion typecopolymer of the present invention. Various copolymerization methods arediscussed herein below.

Various conventional amounts of conventional emulsion polymerizationadditives can also be utilized. Such emulsion polymerization additivesinclude various emulsifiers, various chain transfer agents or extenderswhich act as molecular weight modifiers, various free-radicalinitiators, various chelating agents, various shortstops, electrolytes,and the like. Considering the emulsifiers, they can be any compound wellknown to the art as well as to the literature such as soaps,surfactants, dispersing agents, and the like which are stable at low pH,e.g. 1.5 to 3.5. The surfactants, as well as the other emulsifiers, canbe cationic anionic, or mixtures thereof with nonionics. Examples ofspecific emulsifiers include the various alkyl sulfates, the variousalkyl sulfosuccinates, the various alkyl aryl sulfonates, the variousalpha olefin sulfonates, the various quarternary ammonium salt, thevarious amine salts, the various fatty or resin acid salts, nonyl oroctyl phenol reaction products of ethylene oxide and the like. The alkylportion of the various emulsifiers generally has from 8 to 18 carbonatoms. Naturally, an amount of an emulsifier is utilized to obtain anaqueous emulsion of the various monomers. Generally, such an amount istypically from about 0.5 to about 5 or 6 parts by weight for every 100parts by weight of the monomers. Other surfactants can be utilized suchas those set forth in "Surface Active Agents," Schwartz and Perry, Vol.I, Interscience Publishers, Inc., New York, 1958; "Surface Activity,"Moilliet, Collie and Black, D. Van Nostrand Company, Inc., New York,1961; "Organic Chemistry," Fieser and Fieser, D. C. Heath and Company,Boston, 1944; and "The Merck Index," Seventh Edition, Merck & Co., Inc.,Rahway, N.J., 1960, all of which are hereby fully incorporated byreference.

The various chain extenders or molecular weight regulators can beconventional compounds as well as those known to the art and to theliterature. Accordingly, compounds such as benzene, toluene, triphenylmethane, and carbon tetrachloride can be utilized. However, mercaptanssuch as the alkyl and/or aralkyl mercaptans having from 8 to about 18carbon atoms and preferably from about 12 to about 14 carbon atoms arepreferably utilized. The tertiary alkyl mercaptans having from 12 to 14carbon atoms are highly preferred. Examples of suitable mercaptansinclude n-octyl mercaptan, n-dodecyl mercaptan, t-octyl mercaptan,t-dodecyl mercaptan, p-tridecyl mercaptan, tetradecyl mercaptan,hexadecyl mercaptan, and the like, as well as mixtures thereof. Theamount of the molecular weight modifiers is an effective amount toprovide for the proper retention of the tensile strength of theinterpolymer, for example from about 0.1to about 5.0 parts by weight anddesirably from about 0.2 to about 1.0 parts by weight for every 100parts by weight of the monomers.

Free-radical initiators are utilized to polymerize the various monomersand are utilized in amounts sufficient to obtain a desired molecularweight. A suitable amount is generally from about 0.25 to about 2.0 withfrom about 0.5 to about 1.5 parts being preferred for every 100 parts byweight of the monomers. Conventional free-radical initiators can beutilized as well as those known to the art and to the literature.Specific examples include ammonium persulfate, potassium persulfate, oror sodium persulfate, hydrogen peroxide, and the like. Otherfree-radical initiators can be utilized which decompose or become activeat the temperature utilized during polymerization. Examples of otherfree-radical catalysts include cumene hydroperoxide, dibenzoyl peroxide,diacetyl peroxide, dodecanoyl peroxide, di-t-butyl peroxide, dilauoylperoxide, bis(p-methoxy benzoyl) peroxide, t-butyl peroxy pivalate,dicumyl peroxide, isopropyl percarbonate, di-sec-butylperoxidicarbonate, azobisdimethylvaleronitrile,2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methyl-butyronitrile,2,2'-azobis (methylisobutyrate) and the like and mixtures thereof. It ispreferred to use the inorganic persulfates of which the sodium salt ispreferred since they impart better color to the resulting polymer whendried. Organic hydroperoxides such as t-butyl hydroperoxides arepreferred for the cationic system of the present invention.

Chelating agents can be utilized during polymerization to tie up variousmetal impurities as well as to achieve a uniform polymerization Theamounts of such chelating agents are generally small such as from about0.01 to about 0.25 parts by weight for every 100 parts by weight of themonomers. Examples of suitable chelating agents include ethylene diaminetetraacetic acid, nitrilotriacetic acid, citric acid, and theirammonium, potassium, and sodium salts.

Various shortstop compounds can also be utilized. Not only do theshortstop compounds terminate the polymerization in the reactor atdesired conversion levels, but also prevent further polymerization,crosslinking, etc., during stripping, and the like. Examples of suitableshortshop agents include hydroquinone, sodium sulfide, hydroxyl ammoniumacid sulfate, hydroxyl ammonium sulfate, sodium diethyl dithiocarbamate,diethylhydroxylamine, sodium dimethyl dithiocarbamate, potassiumdimethyl dithiocarbamate, dimethylammonium dimethyldithiocarbamate,hydroxylamine sulfate plus sodium hydrosulfite, and the like. The amountof shortshop utilized is from about 0.05 to about 0.25 parts by weightfor every 100 parts by weight of said monomers. Of course, otherconventional chelating agents as well as shortstops can be utilizedincluding those known to the art and to the literature.

The electrolytes are generally neutral such as the various sulfates, andvarious monobasic salts thereof. These and other electrolytes are knownto the art as well as to the literature. The amount of such electrolytescan generally be from about 0.05 to about 1.0 and preferably from about0.05 to about 0.75 parts by weight for every 100 parts by weight of saidmonomers.

The above description relates to the preparation of an emulsioncopolymer utilizing functional monomers which are generally anionic inaccordance with the dominant practice of forming aqueous emulsions orlatexes. However, it is to be understood that various cationic monomerscan be utilized and that such are sometimes an advantage with regard toadhesion to various substrates, and the like. Whenever such cationicmonomers are utilized, they are utilized in lieu of the above-notedoptional anionic functional monomers. Examples of suitable cationicmonomers include the dimethyl sulfate quaternized product of dimethylamino ethyl methacrylate, the methyl chloride quarternized product ofdimethyl amino ethyl methacrylate, methacryl amino propyl trimethylammonium chloride, dimethyl diallyl ammonium chloride,N(3-chloro-2-hydroxy propyl)trimethyl ammonium chloride,2-hydroxy-3-methacryloyloxy propyl trimethyl ammonium chloride, and theamine monomers dimethyl amino ethyl (meth)acrylate, diethyl amino ethyl(meth)acrylate, tertiary butyl amino ethyl methacrylate and dimethylamino propyl methacrylamide. When cationic monomers are utilized in lieuof the anionic monomers, cationic type surfactants are very desirable.Moreover, the preparation of the copolymers made from such cationicfunctional monomers differs in that cationic additives are utilizedincluding various cationic chain transfer agents or extenders, variouscationic initiators, various cationic chelating agents, various cationicshortstops, and the like. Otherwise, preparation proceeds in a manner asnoted above, for example the cationic monomers are free radicallypolymerized.

Polymerization of the various monomers is carried out at a temperaturesufficient to activate the initiators and the double bonds of themonomers. However, extremely high temperatures are avoided since theycause a run-away reaction. Too low temperatures are not desired sincethey retard polymerization. Suitable polymerization temperatures arefrom about 2° C. to about 90° C., desirably from about 35° C. to about80° C., and preferably from about 65° C. to about 77° C. Polymerizationtime will naturally vary depending upon the type of monomers utilized,the type of initiator utilized, and the degree of polymerizationdesired. Hence, typical polymerization times can range from about 5 toabout 35 hours. Polymerization is generally carried out to completionand conducted in an acidic medium when acidic monomers are utilized.Upon completion of the reaction or the desired degree of polymerization,optional bases can be added to neutralize the latex. Examples of suchoptional bases include NaOH, KOH, NH₄ OH, and the like. However, anacidic latex is desired having a pH of from about 2.0 to 7.0 anddesirably from about 2.0 to about 4.0.

The free radical polymerization can be carried out according to anyconventional method including batch, incremental, or continuous. Thewater used during the polymerization should be free of deleteriousmaterial and hence is often distilled or ion exchanged water. The amountof water used is sufficient to enable the formation of an emulsion andto enable proper mixing of the various ingredients as well as to obtainthe desired rate and degree of polymerization, heat transfer, and thelike. Upon completion of polymerization, the amount of copolymer orsolids content can vary from about 10% to about 60% by weight andpreferably from about 40% to about 55% by weight.

Desirably polymerization is conducted in an inert atmosphere such asnitrogen, helium, argon, and the like and hence it is carried out in aclosed reactor. The reactor can be any conventional reactor and thushave suitable ports, agitation means, heating and cooling means, and thelike. In accordance with conventional practice, the reactors utilizedare generally cleaned as by flushing with water between polymerizationsto remove traces of various initiators. shortstops, residues,surfactants, and the like.

The copolymer latexes of the present invention can be treated with otherconventional additives such as antioxidants, biocides, defoamers, andthe like as known to the art and to the literature.

The latexes of the present invention can be compounded with variousfinely divided fillers such as various paper coating fillers, forexample clays, kaolin, calcium carbonate, titanium dioxide, zinc oxideand other inorganic fillers commonly used in the paper coatingcompositions. Various thickening agents, viscosity stabilizers, and thelike can also be utilized.

The latexes of the present invention can be utilized on variouscellulosic materials such as paper, for example paper towels, coatedpaper, masking tapes, label tapes, containers, or the like. They can beapplied in any conventional manner such a by spraying, by saturation,e.g. dipping the paper into the latex, by coating, and the like. Thelatexes can further be applied to variously formed materials, be theypaper, synthetic fibers such as polyesters, polypropylenes, rayon,nylons, to masking tapes, to carpets, and the like. Another desired areaof use is on various nonwoven textiles. Specific examples include mats,various hospital disposable products such as face masks, gowns, gloves,and the like, as well as commercial applications wherever mats areutilized such as in diapers, and the like. A preferred use is in theapplication of paper since it has been found that the latexes of thepresent invention unexpectedly improved cure rate development.

Once the latexes of the present invention have been applied to asubstrate, they can be cured. Curing generally occurs by heating at atemperature of from about 25° C. to about 180° C. and preferably fromabout 100° C. to about 150° C. Curing can occur as in the presence of aheating means, for example an oven, an electronbeam, infrared heat, orat ambient temperature, or the like.

According to the present invention, the use of two functional monomers,that is an activatable ester monomer and either an acrylamide typemonomer, a methacrylamide type monomer, a vinyl ether type monomer, or acarboxylic acid type monomer, or combinations thereof, has been found togenerally result in a quicker cure time and/or a lower cure temperaturewhen utilized with the various latex monomers. This is desirable sincequicker or faster crosslinking times are useful. Thus, when the resultsof Example 1 are plotted, as in FIG. 1, it is seen that the initial curestrength, that is the wet tensile strength, is much greater forcompounds of the present invention containing an activatable ester aswell as a second functional containing monomer, for example acrylicacid. Cure time is very important in the utilization of latexes in thatshort heating times are highly desirable. For example, in theapplication of coatings to cellulosic material such as towels, quickcure times are desired. Example 1, as well as FIG. 1, also reveals thatimproved wet strengths are obtained utilizing a second functionalmonomer. That is at all cure times, large absolute improvement values inthe wet tensile strength are obtained. Considering Example 2 as well asFIG. 2, it is once again apparent that utilization of a secondfunctional monomer such as acrylamide yields great improvements in theinitial cure time, that is the initial slope of the various curves. Moreimportantly, as set forth in Example 2, dramatic improvements in the wettensile strength are obtained and thereby conclusively proving that asynergistic result is obtained.

In general, use of the second or more functional type monomers resultsin an absolute value increase in the wet tensile strength at generallyany given cure time. For example, at 300 seconds of at least 1.5,desirably 2.0, and preferably 2.5 lbs/in.

The invention will be better understood by reference to the followingexamples.

The test method utilized in the examples for measuring wet tensilestrength is as follows:

Whatman #4 chromatographic paper die-cut to 8"×10" is used with atolerance of ±5.0% in an untreated weight basis. The sheets aresaturated with the latex using a laboratory padder at a binder add-ontarget of 20±1.5% based on the finished sheet weight The saturatedsheets are air dried at room temperature and then duplicate sheets arecured on the steam heated drier cans at 315° F. for 15, 30, 60, and 300seconds. All sheets are conditioned in accordance with TAPPI test methodT402 before testing. Then they are immersed in distilled water untilthey are completely wetted. The tensile is then determined on four teststrips in both the machine direction (MD) and in the cross direction(CD) for each cured sheet. The average of the eight results in eachdirection and the total tensile is reported as the sum of the CD and MDaverages. This result is normalized to a basic weight of 73.0 lbs./300ft. and a binder add on of 20%.

EXAMPLE I

Bottle scale polymerizations were carried out using the ingredients setforth below. In each case an initial charge was made to the bottlesusing the ingredients in the order listed in the table. The bottles wereflushed with nitrogen, capped, and allowed to react 45 minutes at 65° C.

The bottles were opened, recharged with the appropriate amount ofstyrene, Sulfole 120 and butadiene, as listed in the table. This chargewas reacted until the bottles were under vacuum as a result of most ofthe monomers having reacted. The bottles were opened a second time andfurther monomers, Sulfole 120, MAGME, and other cofunctional monomersadded, as listed. This charge was also reacted to vacuum. The latexesobtained were tested without stripping. Some latexes were tested at thepH of the finished latex while others were tested at a pH of about 7.5after adjustment with ammonium hydroxide.

    ______________________________________                                        LATEX                                                                                          A     B     C   D   E   F   G   H                            ______________________________________                                        INITIAL CHARGE                                                                Water, ml        68    68    68  68  68  68  68  68                           Solution A, ml   40    40    40  40   0   0   0   0                           Solution B, ml    0     0     0   0  40  40  40  40                           Solution C, ml   60    60    60  60  60  60  60  60                           Solution D, ml   18    18    18  18  18  18  18  18                           Styrene, gms     15    15    15  15  15  15  15  15                           Reacted 45 minutes @ 65° C.                                            FIRST CHARGE BACK                                                             Styrene, gms     36    36    40  36  38  34  35  34                           Solution E, gms  10    10    10  10  10  10  10  10                           Butadiene, gms   40    40    40  40  40  40  40  40                           Reacted to vacuum                                                             SECOND CHARGE BACK                                                            Water, ml         0     0    42   8  40   6  29  13                           Solution F, ml   53    53    11  53  11  53  53  53                           Solution D, ml   10    10    10  10  10  10  10  10                           Solution G, gms   0     0     0   0   4   4   0   0                           Hydroxyethyl                                                                  Acrylate, gms     0     0     0   0   0   0   2   4                           Styrene, gms     36    18    40  36  38  34  35  34                           Solution E, gms  10    10    10  10  10  10  10  10                           Solution H, gms   0    20     0   0   0   0   0   0                           Butadiene, gms   40    40    40  40  40  40  40  40                           Reacted to Vacuum                                                             Solution A  0.4% (weight/volume i.e., W/V)                                    Dowfax 2A-1, 2.5%                                                                         (W/V) Sipex BOS,                                                              1.5% (W/V) Aerosol MA, and 0.25%                                              (W/V) Sequestrene Na-3 in deionized                                           water.                                                            Solution B  Same as A except 0.425% (W/V) Dowfax                                          2A-1                                                              Solution C  5.0% (W/V) itaconic acid in deionized                                         water                                                             Solution D  5.0% (W/V) sodium persulfate in                                               deionized water                                                   Solution E  3.8% (W/V) Sulfole 120 in styrene                                 Solution F  18.9% (W/V) MAGME in deionized water                              Solution G  50% (W/W) acrylamide in deionized water                           Solution H  20% (W/W) acrylic acid in styrene                                 ______________________________________                                        LATEX PROPERTIES                                                                       A      B      C    D    E    F    G    H                             ______________________________________                                        Total Solids,                                                                          44.9   44.1   44.6 44.3 44.4 44.1 45.0 44.6                          pH       2.3    2.2    2.5  2.2  2.6  2.2  2.2  2.1                           Brookfield                                                                             27     29     27   30   27   42   35   36                            Viscosity,                                                                    cps.                                                                          Surface  45.7   44.7   49.7 44.6 47.1 44.3 42.8 42.8                          Tension,                                                                      dynes/cm                                                                  

Latexes A and B of the bottle scale series relate to the use of MAGME incombination with acrylic acid and the use of itaconic acid in theinitial step. These latexes both had 5 parts of MAGME and 0 and 2 partsrespectively of acrylic acid.

Both latexes were tested in the Whatman #4 paper without steam strippingbut with the pH adjusted to 7.5 by ammonium hydroxide. Latex B was alsotested at 2.5 pH before adjustment Results for total wet tensilestrength were as follows:

    ______________________________________                                                 A       B           B                                                         (Control)                                                                             (Acrylic Acid)                                                                            (Acrylic Acid)                                   ______________________________________                                        pH         7.5       7.5         2.5                                          Cure Time, Secs.                                                               15        22.3      25.0        26.9                                          30        26.9      27.0        30.1                                          60        28.7      30.4        29.9                                         300        31.9      34.1        29.6                                         ______________________________________                                    

It is evident that Latex B which contains both acrylic acid and MAGME isbetter than Latex A which contains only MAGME. Not only did both "B"examples have a faster cure rate, but a higher wet tensile strength wasalso obtained. Thus, synergistic results were obtained.

EXAMPLE 2

Latexes C, D, E, and F of the bottle series illustrate the use ofacrylamide with MAGME and the synergistic effect thereof. Test resultsfor total wet tensiles of Whatman #4 paper saturated with these latexesat low pH are as follows:

    ______________________________________                                        Latex         C      D          E    F                                        ______________________________________                                        MAGME, PHM    1      5          1    5                                        Acrylamide, PHM                                                                             0      0          1    1                                        ______________________________________                                        Cure Time, Secs.                                                                            Total Wet Tensiles                                              ______________________________________                                         15           16.9   25.0       18.3 33.0                                      30           18.2   26.1       21.1 33.8                                      60           19.8   27.6       22.3 32.8                                     300           19.4   27.7       25.5 30.9                                     ______________________________________                                    

It is apparent from the above that increases in either MAGME oracrylamide (when the other is held constant) yield improved wet tensilestrengths and increased cure rates at low cure times. For example, at 15seconds and no acrylamide (C and D) increasing the MAGME from 1 to 5parts increases the wet tensile (25.0-16.9)=8.1 units. Increasing theacrylamide from 0 to 1 part (C and E) increases the wet tensile at 15second cure (18.3-16.9)+1.4 units. However, increasing both MAGME andacrylamide (C compared with E) results in an improvement (33.0-19.4) of13.6 units which is much more than the sum of the individual(8.1+1.4=9.5) effects and hence a synergistic result.

EXAMPLE 3

This example relates to the fact that a single anionic surfactants,Aerosol MA, can also be used to produce latexes. The latexes wereprepared in bottles using 0.78 PHM of Aerosol MA-80 as the onlysurfactant.

    ______________________________________                                                    I         J      K                                                ______________________________________                                        MAGME         3.5         5.0    5.0                                          Acrylic Acid  0           2      0                                            Acrylamide    2           0      2                                            Coagulum,     0.4         0.4    0.4                                          wet gms, %                                                                    pH            2.2         2.1    2.1                                          Total Solids, %                                                                             39.9        39.9   40.8                                         Viscosity     18          18     18                                           Surface Tension,                                                                            38.9        38.9   38.9                                         dynes/cm                                                                      ______________________________________                                    

EXAMPLE 4

This example relates to the preparation of latexes in bottles using acationic system. The ingredients and latex properties are set forth inthe following table:

    ______________________________________                                        LATEXES                                                                                       L   M      N     O    P   Q                                   ______________________________________                                        INITIAL CHARGE                                                                Water, Ml         64    64     64  64   64  64                                Solution A, ml    40    40     40  40   40  40                                Solution B, ml    15    15     15  15   15  15                                Solution C, ml     8     8      8   8    8   8                                Solution D, ml    40    40     40  40   40  40                                Solution E, ml     8     8      8   8    8   8                                Styrene, gm       15    15     15  15   15  15                                Reacted 45 minutes @ 65° C.                                            Solution F, ml     8     8      8   8    8   8                                Styrene, gms      31    29     30  28   29  27                                Solution G, gms   10    10     10  10   10  10                                Solution E, gms    4     4      4   4    4   4                                Butadiene         40    40     40  40   40  40                                Reacted to Vacuum                                                             SECOND CHARGE BACK                                                            Water, ml         29     4     27   2   25   0                                Solution F, ml     8     8      8   8    8   8                                Solution H, ml    40    67     40  67   40  67                                50% acrylamide, gms                                                                              0     0      4   4    8   8                                Styrene, gms      27    25     26  24   25  23                                Solution G, mgs   10    10     10  10   10  10                                Solution E, mgs    8     8      8   8    8   8                                Butadiene, gms    40    40     40  40   40  40                                ______________________________________                                    

Raised temperature to 170° F. and reacted to vacuum.

    ______________________________________                                        70% t-butyl    0.4   0       0.4 0     0.4 0.4                                hydroperoxide, gms                                                            ______________________________________                                    

Solution A--7.0% (W/V) Arquad C-33 is deionized water

Solution B--4.8% (W/V) aluminum chloride - hexahydrate in water

Solution C--5.0% (W/V) sodium chloride in water

Solution D--7.5% (W/V) Sipomer Q-5-80 in water

Solution E--3.5% (W/V) t-butyl hydroperoxide in styrene

Solution F--12.5% (W/V) Arquad C-33 in water

Solution G--3.75% (W/V) Sulfole 120 in styrene

Solution H--15.0% (W/V) MAGME in water

    ______________________________________                                        LATEX PROPERTIES                                                                      L     M       N       0     P     Q                                   ______________________________________                                        Total Solids, %                                                                         43.4    41.8    43.5  42.0  43.2  41.0                              pH        2.3     2.1     2.4   2.1   2.4   2.4                               Viscosity 19      21      21    20    32    18                                Surface Tension                                                                         39.9    45.7    43.8  42.8  40.9  39.9                              ______________________________________                                    

All latexes were essentially coagulum free.

    ______________________________________                                        CHEMICAL DEFINITIONS:                                                         ______________________________________                                        MAGME    Methyl acrylamidoglycolate methyl ether                                       CH.sub.2 = CH--CONHCHOCH.sub.3 COOCH.sub.3                                    American Cyanamid Company                                            Sequestrene                                                                            Trisodium ethylene diamine tetra acetate                             Na-3     dihydrate                                                                     Ciba-Geigy Corp.                                                     Aerosol MA                                                                             Bis(1-methlamyl) sodium sulfosuccinate                                        American Cyanamid Co. an anionic surfactant.                                  80% in water.                                                        Sipex BOS                                                                              Sodium 2-ethyl hexyl sulfate                                                  Alcolac Inc. 40% aqueous solution.                                   Sulfole 120                                                                            t-dodecyl mercaptan, avg. mol. wt. 198 Calc.                                  purity wt. 96.8%                                                              and mercaptan sulfur wt. 15.4%                                                Phillips Petroleum Co., Rubber Division                              Arquad C-33                                                                            Trimethyl cocoammonium chloride                                               Armak Co. - 33% aqueous solution.                                    Sipomer  Dimethyl sulfate quarternary of                                      Q-5-80   dimethylamino-ethyl methacrylate                                              CH.sub.2 = C(CH.sub.3)COOCH.sub.2 CH.sub.2 N.sup.+ (CH.sub.3).sub             .3 CH.sub.2 OSO.sub.3                                                         80% aqueous solution. Alcolac, Inc.                                  ______________________________________                                    

While in accordance with the patent statutes, a best mode and preferredembodiment has been set forth in detail, the scope of the presentinvention is limited by the scope of the attached claims.

What is claimed is:
 1. A cured emulsion copolymer, comprising:anemulsion copolymer made in the presence of water and surfactants frompolymerized monomers of (1) at least one latex forming monomer and (2)at least one functional type monomer having an activatable ester groupand a vinyl group with (3) at least one second functional type monomerto form an emulsion containing a copolymer, said emulsion polymersubsequently cured, said latex forming monomer being a conjugated diene,or a conjugated diene and at least one different conjugated dienecomonomer having from 4 to 8 carbon atoms, or a conjugated diene and avinyl substituted aromatic comonomer having from 8 to 12 carbon atoms,wherein the total amount of said functional monomers is from 0.5 percentto about 15 percent by weight based upon the total weight of saidemulsion copolymer forming monomers, wherein the amount of said latexforming monomer is from about 85 percent to about 99.5 percent by weightbased upon the total weight of said emulsion copolymer forming monomers,and wherein said second type functional monomer is an acrylamide or a 1to 2 carbon atom alkyl derivative thereof, a methacrylamide or a 1 to 2atom alkyl derivative thereof; or combinations thereof.
 2. A curedemulsion copolymer according to claim 1, wherein said alkyl derivativeof said acrylamide functional monomer having 1 to 2 carbon atoms isattached to either the nitrogen atom, the vinyl group, or both, andwherein said alkyl derivative or said methacrylamide functional monomerhaving 1 to 2 carbon atoms is attached to either the nitrogen atom, thevinyl group, or both, and wherein said copolymer is cured at atemperature of from about 25° C. to about 180° C.
 3. A cured emulsioncopolymer according to claim 2, wherein said conjugated diene and saiddifferent conjugated diene has from 4 to 6 carbon atoms, wherein theamount of said conjugated diene comonomer is from about 1 percent toabout 99 percent by weight based upon the weight of the total monomers,wherein the amount of said vinyl substituted aromatic comonomer is from0 percent to 70 percent by weight based upon the weight of the totalmonomers;wherein the total amount of said functional monomers is fromabout 1 percent to about 10 percent by weight based upon the weight ofthe total monomers, wherein the amount of said latex forming monomer isfrom about 90 percent to about 99 percent by weight based upon theweight of the total monomers, and wherein said activatable ester monomerismethyl acrylamidoglycolate (MAG) ethyl acrylamidoglycolate (EAG) butylacrylamidoglycolate (BAG) methyl acrylamidoglycolate methyl ether(MAGME) butyl acrylamidoglycolate butyl ether (BAGBE) methylmethacryloxyacetate ethyl acrylamido-N-oxalate (N-ethyloxalylacrylamide) N,N'-bis(ethyloxalyl)acrylamideN-isopropyl-N'-ethyloxalyl-3-propylaminomethacrylamideN-ethyloxalyl-N'-methyleneaminoacrylamide ethyl N-2-ethyloxamatoacrylateethyl 3-pyruvylacrylate ethyl methylenepyruvate methylacrylthiocarbonyloxyacetate (methyl thiacryloxyacetate) methylthiacrylthioglycolate methyl acryl-2-thioglycolate methylthiacrylamidoacetate methyl acrylamidoglycolate thioether methylacrylamido-N-methylenethioglycolate, or p-ethyl oxalyl styrene.
 4. Acured emulsion copolymer according to claim 3,wherein said secondfunctional monomer is acrylamide or methacrylamide, and wherein saidfunctional activatable ester monomer is methacrylamidoglycolate,methacrylamidoglycolate methyl ether, butylacrylamidoglycolate, orbutylacrylamidoglycolate butyl ether, or combinations thereof.
 5. Acured emulsion copolymer according to claim 4, wherein the amount ofsaid latex forming monomer is from about 94 percent to about 97 percentby weight, and wherein the total amount of functional monomers is fromabout 3 percent to about 6 percent by weight, and wherein said curingtemperature is from about 100° C. to about 150° C.